1. Field of the Invention
The present invention relates to an ink jet printer with a maintenance cap for protecting ink ejection nozzles formed in a nozzle surface of a print head, and for providing a sealed condition around the nozzles so purging to maintain good ejection conditions can be performed.
2. Description of the Related Art
One known ink jet printer includes an ink jet head having a single nozzle plate formed with rows of nozzles. FIG. 1 shows a conventional maintenance cap 100 used to contact the nozzle plate to form a sealed space around the nozzles so purging can be effectively performed. The maintenance cap 100 includes a body 103 and a lip portion 105 integrally formed from rubber. An opening 101 is formed in the body and surrounded by the lip portion 105.
Before a purge operation, the lip portion 105 is brought into intimate sealing contact with the nozzle plate of the ink jet head, so that the nozzle rows in the nozzle plate are surrounded by the lip portion 105 and exposed in the opening 101. Then a suction pump (not shown) connected to the maintenance cap 100 is operated to produce a negative pressure in the opening 101. Ink is drawn by the negative pressure from the nozzles into the opening, and to a waste ink tank (not shown). Dried ink, air bubbles, dust, and the like are flushed out of the nozzles with the flow of ink, so that good ejection condition can be maintained.
It is sometimes desirable to perform purge operations separately for different nozzle rows, for example, when each nozzle row is specifically for ejecting a particular color ink. However, when the conventional maintenance cap 100 is used for purge operations, all nozzle rows surrounded by the lip portion 105 are purged at the same time. Accordingly, with the conventional maintenance cap 100, even nozzle rows that do not need purging are purged together with the desired nozzles, so ink is wasted.
Also, the conventional cap member 100 can easily deform because it is formed entirely from rubber. Therefore, the lip portion 105 can collapse under the negative pressure developed in the opening 101 during a suction operation, and cover the nozzles of the ink jet head. Also, rubber is slightly permeable to air, so the opening 101 in the cap 100 can be in an insufficiently airtight condition during suction operations.
It is a first objective of the present invention to provide a maintenance cap that enables purging nozzle rows separately.
It is a second objective of the present invention to achieve the first objective without increasing the size of the maintenance cap.
It is a third objective of the present invention to provide a cap member with a lip portion that will not collapse under negative pressure during suction operations and that has reliable airtight properties.
In order to achieve the first objective, a cap member according to a first aspect of the present invention for covering, during suction operations, nozzle rows formed in a single nozzle plate of an ink jet head of an ink jet printer, includes a surrounding lip, a partitioning lip, and a body. The surrounding lip is for forming a sealed condition around the nozzle rows when in intimate contact with the nozzle plate during suction operations. The partitioning lip is for forming, with the outer lip portion, partitioned spaces that separate the nozzle rows from each other. The body s connected to the surrounding lip and the partitioning lip, and is formed with a separate suction hole for each partitioned space.
With this configuration, because the partitioning lip separates nozzle rows from each other, and because a suction hole is provided for each space partitioned by the partitioning lip, when a suction operation for preventing nozzle clogs is performed on an ink jet head with a nozzle plate formed with a plurality of nozzle rows, then each nozzle row in each partitioned space can be separately suctioned. Therefore, only a minimal amount of ink required to effectively purge desired nozzles is used, because nozzle rows that do not need to be purged are not purged.
It is desirable that the surrounding lip and the partitioning lip according to the first aspect of the present invention be elongated in a lengthwise direction in parallel with each other, to form elongated and parallel aligned partitioned spaces for separating nozzle rows that are parallel aligned and separated from each other in a widthwise direction perpendicular to the lengthwise direction. With this configuration, when the cap member covers the nozzle plate, each nozzle row is sealed in a separate partition space provided with an individual suction hole. Therefore, suction operations can be performed separately for each nozzle row, so that only desired rows of all the nozzle rows are purged.
In order to achieve the second objective, it is desirable that the body according to the first aspect of the present invention be formed with the suction holes for each partitioned space positioned shifted from each other by a distance in the lengthwise direction. With this configuration, suction tubes connected to the suction holes can overlap in the direction perpendicular to the direction in which the nozzle rows extend. Therefore, the cap member can be produced in a small size.
It is desirable that the surrounding lip according to the first aspect of the present invention be elongated in a lengthwise direction and the partitioning lip is be elongated in a widthwise direction perpendicular to the lengthwise direction, to form elongated and linearly aligned partitioned spaces for separating linearly aligned nozzle rows. With this configuration, even if the plurality of nozzles are linearly aligned, each nozzle row is sealed within an independent partitioned space during suction operations. Because a suction hole is provided for each partitioned space, these suction holes can be used to perform suction operations only on desired nozzle rows, so that ink is not wasted.
It is desirable that the body according to the first aspect of the present invention be formed from resin and include an integral base portion and protruding portion. In this case, the suction holes are formed in the base portion, the protruding portion protrudes away from the base portion, and at least one of the surrounding lip and the partitioning lip covers the protruding portion.
In order to achieve the third objective, a cap member according to a second aspect of the present invention includes a resin body, and a resilient rubber lip member. The resin body includes an integral base portion and protruding portion. The protruding portion protrudes away from the base portion. The resilient rubber lip member is adapted for intimate sealing contact with the ink jet head, and covers at least the protruding portion of the resin body.
With this configuration, the base portion and the protruding portion are formed integrally together from resin as the body. Therefore, when a suction operation is performed to prevent nozzles from clogging, the rubber lip portion will not collapse. Also, the portion of the lip portion that needs to be formed from rubber is minimized. Because synthetic resin has high airtight properties, a reliable sealed condition can be maintained during suction operations.
It is desirable that the protruding portion according to the second aspect of the present invention be elongated in at least a lengthwise direction of the base portion, so that the lip member can be reliably supported by the protruding portion. Therefore, the lip portion can be effectively prevented from collapsing during suction operations.
It is desirable that the lip member according to the second aspect of the present invention include a surrounding lip and a partitioning lip. The surrounding lip is for forming a sealed condition around a plurality of nozzle rows formed in the nozzle plate of the ink jet head. The partitioning lip is for forming, with the surrounding lip, partitioned spaces that sealingly separate the nozzle rows from each other. In this case, it is further desirable that the body according to the second aspect of the present invention be connected to the surrounding lip and the partitioning lip, and be formed with a separate suction hole for each partitioned space.
It is desirable that the lip member according to the second aspect of the present invention be mounted on the protruding portion, and protrude away from the protruding portion to a distance less than a protruding distance of the protruding portion. Because the lip member is mounted thinly on the surface following the shape of the protruding portion, the lip portion can be effectively prevented from collapsing during purge operations.
It is desirable that the lip member according to the second aspect of the present invention be formed with a thickness of 1.0 mm or less. With this configuration, the lip member can be effectively prevented from collapsing without the lip member protruding greatly upward away from the protruding portion. Also, because air can pass through rubber, increasing the thickness of the rubber lip member greater than 1.0 mm will reduce airtight properties of the cap member. Therefore, it is desirable to form the lip member with a thickness of 1.0 mm or less.
When the lip member is formed with a rectangular shape as viewed in plan, and the lengthwise edge is 10 mm or greater, the problem of the lip portion collapsing under negative pressure of suction operations increases dramatically. However, because the rubber lip portion is supported by the protruding portion, the problem of the lip portion collapsing under negative pressure of suction operations can be overcome.
It is desirable that the lip member according to the second aspect of the present invention be formed from a rubber material with hardness of 40xc2x0 or greater. Hardness is defined in accordance with JIS K 6301. With this configuration, the lip portion can be effectively prevented from collapsing under negative pressure during suction operations.